function ajax_update(type,url,data,target,callback){
   $.ajax({
     type: type,
     url: url,
     data: data,
     success: function(html){
	   $(target).hide();
	   $(target).html(html);
	   $(target).fadeIn("fast");
	   callback;
     }
   });
}

function ajax_done(type,url,data,callback){
   $.ajax({
     type: type,
     url: url,
     data: data,
     success: function(html){
	   callback(html);
     }
   });
}
/*
function ajax_update2(type,url,data,target,callback){
   $.ajax({
     type: type,
     url: url,
     data: data,
     success: function(html){
	   $(target).html(html);
	   var t=setInterval(callback,4000);
     }
   });
}
*/